1. Field of the Invention
This invention relates to a caster structure for a treadmill runner. This structure enables the treadmill runner's frame to be pushed directly after its running board and framework have been moved to their upright folding positions.
2. Description of the Prior Art
A treadmill runner is a track type sport facility used for indoor exercise. Its typical assembly is to have one floor-type front prop and one floor-type rear prop installed at front and rear ends of the treadmill runner's framework. The running board can be set to demonstrate a slightly tilted status when the placement of the framework is done. At this moment, the user can run on the running track to do the running exercise. When storage or transportation of the treadmill runner by folding is desired, the user can flip the running board into an upright folding position to lessen its space occupation.
In a known treadmill design (as shown on FIG. 1), after running board 12 is lifted to a vertical status, its floor-type front prop 14 will become the supporting point and will bear the total weight of runner frame 10. Afterward, there are caster assemblies 16 equipped on both ends of one side of the floor-type prop 14. Therefore, moving the runner frame 10 can be done by just simply slanting runner frame 10 in an adequate angle and letting the caster assemblies touch floor 18 to perform their work (as shown by dashed lines in the figure), and then smoothly pushing runner frame 10. The integrated weight of runner frame 10 is not a light weight. When it is tilted to its push-to-move position, the floor-type prop 14 has completely separated from floor 18 leaving the caster assemblies 16 as the only supporting points. Under these circumstances, runner frame 10 may fall down onto the ground 18 due to user's careless incident or obstacles on the ground while the user is pushing the runner frame 10 without paying special attention to the surrounding environment. As a result, this may seriously damage the runner frame 10 and hurt the user.